Interior walls of office buildings, homes, apartments, etc., are usually of so-called drywall construction which has poor nail and screw holding power except at the location of the studs. A common form of hollow wall anchor is the toggle-screw anchor, e.g. MOLLY brand screw anchor. In the installation of such screw anchor, a hole is drilled through the wall and the anchor is pushed through the hole with its flange engaging the front side of the wall and generally the screw head of the anchor is tapped with a hammer to embed the spurs of tangs of the flange of the anchor sleeve into the wall. Thereafter the screw is turned with a screwdriver under considerable torque and axial pressure to initiate drawing of the threaded end of the anchor sleeve toward the flanged end to cause collapsing of the intermediate section of the anchor sleeve into gripping engagement with the rear side of the wall. Occasionally the large forces applied by the screwdriver may cause the flanged end of the anchor sleeve to be pushed through the wall especially if the hole in the wall is oversize. Moreover, if the hole in the wall is not perpendicular to the wall the screwdriver is ineffective to correctly position the collapsed anchor sleeve perpendicular to the wall.
Known tools for installation of toggle-screw anchors as disclosed for example in the U.S. Pat. Nos. to Hollwarth 2,428,458 and Coloma 4,038,851 are of complex and expensive construction and operate on the principle of pivoted toggle levers which are operative to axially draw the threaded end of the anchor sleeve toward the flanged end for collapsing the same. In these constructions the levers are spread apart in use and hence are not suitable for installation of toggle-screw anchors in close quarters as in the corner of a room, near the ceiling or floor.
In my copending application Ser. No. 971,346, filed Dec. 20, 1978, now U.S. Pat. No. 4,201,072, the tool for installation of toggle-screw anchors includes an L-shaped body of injection molded plastic material having an elongated tubular leg for the anchor sleeve collapsing screw and an elongated radially extending leg which is perpendicular to the tubular leg and has a planar wall-engaging surface flush with the inner end of the tubular leg. The anchor sleeve collapsing screw has a head adjacent to the outer end of the tubular leg with wrench-engaging flats or with a cross bar by means of which high torque may be applied on the screw for causing collapse of the anchor sleeve without imposing push-through axial pressure on the flange of the anchor sleeve and while holding the actuating screw and anchor sleeve perpendicular to the wall by holding the radially extending leg against the wall and against turning.